A DC power supply device disclosed in Patent Literature 1 below is configured to short-circuit a switch unit only once during a half cycle of a power supply to allow a current to pass through a reactor, reduce a harmonic current, and improve a power factor. However, in order to reduce harmonics by short-circuiting the switch unit only once during the half cycle of the power supply, an inductance value of the reactor needs to be increased, which increases heat generated in the reactor. This is because an input current that is reduced to zero after allowed to flow by the operation of the switch unit not only reduces the power factor but also causes the amount of higher order harmonics to be larger than usual. Moreover, when the short circuit is made only once, a large amount of energy needs to be stored in the reactor to prevent the input current from being zero.
A conventional technology according to Patent Literature 2 below short-circuits the switch unit twice or more during the half cycle of the power supply so that the inductance value of the reactor and the heat generation can be reduced. Moreover, the reduction in the inductance value reduces the outer shape of the reactor, thereby the size of the reactor can be reduced.